Optical film and a liquid crystal display including the same

ABSTRACT

An optical film is provided. The optical film includes a base film and a cover film. The base film includes a base member and a plurality of lens patterns disposed on the base member. The plurality of lens patterns protrudes from the base member and extends in a first direction. The cover film is disposed on the base film to cover the base member and the plurality of lens patterns. A refractive index of at least one of the lens patterns is smaller than a refractive index of the cover film. An aspect ratio of the at least one of the lens patterns ranges from 0.8 to 1.6.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 10-2014-0182934, filed on Dec. 18, 2014, in the KoreanIntellectual Property Office, the disclosure of which is incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present invention relates to an optical film and a liquid crystaldisplay including the same.

DISCUSSION OF THE RELATED ART

A liquid crystal display may include a thin film transistor, a pixelelectrode, a common electrode, and liquid crystal interposed between twosubstrates facing each other.

A viewing angle of a liquid crystal display may refer to a maximum angleat which the display can be viewed with acceptable visual performance.

SUMMARY

According to an exemplary embodiment of the present invention, anoptical film is provided. The optical film includes a base film and acover film. The base film includes a base member and a plurality of lenspatterns disposed on the base member. The plurality of lens patternsprotrudes from the base member and extends in a first direction. Thecover film is disposed on the base film to cover the base member and theplurality of lens patterns. A refractive index of at least one of thelens patterns is smaller than a refractive index of the cover film. Anaspect ratio of the at least one of the lens patterns ranges from 0.8 to1.6.

In an exemplary embodiment of the present invention, the refractiveindex of the cover film may be larger than the refractive index of theat least one of the lens patterns by 0.1 to 0.65.

In an exemplary embodiment of the present invention, at least one of thelens patterns may have a shape of a lenticular lens or an ellipticallens.

In an exemplary embodiment of the present invention, the refractiveindex of the at least one of the lens patterns may range from 1.0 to1.49.

In an exemplary embodiment of the present invention, the refractiveindex of the at least one of the lens patterns may range from 1.42 to1.49.

In an exemplary embodiment of the present invention, the refractiveindex of the cover film may range from 1.5 to 1.65.

In an exemplary embodiment of the present invention, the refractiveindex of the cover film may range from 1.57 to 1.65.

In an exemplary embodiment of the present invention, the optical filmmay further include an adhesive layer formed on the base member andformed on a surface opposite to a surface on which the cover film isformed.

According to an exemplary embodiment of the present invention, anoptical film is provided. The optical film includes a cover film. Thecover film includes intaglios of a plurality of lens patterns extendingin a first direction. An aspect ratio of at least one of the intagliosof the lens patterns ranges from 0.8 to 1.6. A refractive index of thecover film ranges from 1.5 to 1.65.

In an exemplary embodiment of the present invention, the optical filmmay further include a base film. The base film may be attached to asurface of the cover film on which each of the intaglios of the lenspatterns is formed.

In an exemplary embodiment of the present invention, the optical filmmay further include an air layer in the intaglios of the lens patternsdisposed between the cover film and the base film.

In an exemplary embodiment of the present invention, the optical filmmay further include an adhesive formed on a first portion of a surfacebetween the cover film and the base film. The intaglios of the lenspatterns may not be formed on the first portion of the surface.

In an exemplary embodiment of the present invention, the optical filmmay further include a filling layer disposed in the intaglios of thelens patterns of the cover film. A refractive index of the filling layermay range from 1.0 to 1.49.

In an exemplary embodiment of the present invention, at least one of thelens patterns may have a shape of a lenticular lens or an ellipticallens.

According to an exemplary embodiment of the present invention, a liquidcrystal display is provided. The liquid crystal display includes abacklight unit, a liquid crystal panel, and an optical film. The liquidcrystal panel receives light from the backlight unit to display animage. The optical film is disposed on an upper side of the liquidcrystal panel. The optical film includes a plurality of lens patternsextending in a first direction, and an aspect ratio of at least one ofthe lens patterns ranges from 0.8 to 1.6.

In an exemplary embodiment of the present invention, the optical filmmay include a base film and a cover film. The base film may include abase member and the plurality of lens patterns. The cover film may beformed on the base film to cover the base member and the plurality oflens patterns. The refractive index of the at least one of the lenspatterns may be smaller than a refractive index of the cover film.

In an exemplary embodiment of the present invention, the refractiveindex of the at least one of the lens patterns may range from 1.0 to1.49, and the refractive index of the cover film may range from 1.5 to1.65.

In an exemplary embodiment of the present invention, the optical filmmay include a cover film which is attached to an upper side of theliquid crystal panel, and the plurality of lens patterns may be formedas intaglios in the cover film.

In an exemplary embodiment of the present invention, the liquid crystaldisplay may further include an adhesive formed on a first portion of asurface between the cover film and the liquid crystal panel. Theintaglios of the lens patterns may not be formed on the first portion ofthe surface.

In an exemplary embodiment of the present invention, the liquid crystaldisplay may further include an air layer or a filling layer. The airlayer may be disposed in each of the intaglios of the lens patterns. Thefilling layer may be disposed in each of the intaglios of the lenspatterns. A refractive index of the filling layer may range from 1.0 to1.49, and a refractive index of the cover film may range from 1.5 to1.65.

According to an exemplary embodiment of the present invention, a liquidcrystal display is provided. The liquid crystal display includes aliquid crystal panel and an optical film. The liquid crystal paneldisplays an image. The optical film is disposed on an upper side of theliquid crystal panel. The optical film includes a plurality of lenspatterns extending in a first direction. A refractive index of at leastone of the lens patterns ranges from 1.0 to 1.49. An aspect ratio of theat least one of the lens patterns ranges from 0.8 to 1.6.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the attached drawings, in which:

FIG. 1 is a perspective view of an optical film according to anexemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view of the optical film taken along lineA-A′ of FIG. 1;

FIG. 3 is a cross-sectional view of the optical film taken along lineB-B′ of FIG. 1;

FIG. 4 is a perspective view showing a base film in the optical film ofFIG. 1;

FIG. 5 is a cross-sectional view of the base film of FIG. 4;

FIG. 6 is a perspective view of an optical film according to anexemplary embodiment of the present invention;

FIG. 7 is a cross-sectional view of the optical film of FIG. 6;

FIG. 8 is a cross-sectional view of an optical film according to anexemplary embodiment of the present invention;

FIG. 9 is a cross-sectional view of an optical film according to anexemplary embodiment of the present invention;

FIG. 10 shows a process of fabricating the optical film of FIG. 9according to an exemplary embodiment of the present invention;

FIG. 11 is a cross-sectional view showing an optical film according toan exemplary embodiment of the present invention;

FIG. 12 is a cross-sectional view showing a state where an optical filmaccording to an exemplary embodiment of the present invention isattached to a liquid crystal panel;

FIG. 13 is a cross-sectional view showing a state where an optical filmaccording to an exemplary embodiment of the present invention isattached to a liquid crystal panel;

FIG. 14 is a cross-sectional view showing a liquid crystal displayaccording to an exemplary embodiment of the present invention; and

FIG. 15 is a cross-sectional view showing a liquid crystal displayaccording to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of the present invention will hereinafter bedescribed with reference to the accompanying drawings. However, thepresent invention may be embodied in different forms and should not beconstrued as limited to the exemplary embodiments disclosed herein. Thesame reference numerals may refer to the same elements throughout thespecification and drawings. In the drawings, sizes and relative sizes oflayers and areas may be exaggerated for clarity.

Hereinafter, exemplary embodiments of the present invention will bedescribed with reference to the accompanying drawings.

FIG. 1 is a perspective view of an optical film according to anexemplary embodiment of the present invention. FIG. 2 is across-sectional view of the optical film taken along line A-A′ ofFIG. 1. FIG. 3 is a cross-sectional view of the optical film taken alongline B-B′ of FIG. 1. FIG. 4 is a perspective view showing a base film inthe optical film of FIG. 1. FIG. 5 is a cross-sectional view of the basefilm of FIG. 4.

Referring to FIGS. 1 to 5, the optical film may include a base film 100including a base member 110 and a plurality of lens patterns 120. Thelens patterns 120 may be formed on the base member 110 to protrude fromthe base member 110 and extend in one direction. The optical film mayfurther include a cover film 200 formed on the base film 100 to coverthe base member 110 and the lens patterns 120.

The lens patterns 120 may be formed on the base member 110 to extend inone direction. As shown in FIG. 4, the lens patterns 120 may be formedto be spaced apart from each other and extend in one direction. Further,the lens patterns 120 may be formed to be spaced apart from each otherand extend in parallel to each other. Further, the base member 110 andthe lens patterns 120 may be formed integrally or formed ofsubstantially the same material, but the present invention is notlimited thereto.

Each of the lens patterns 120 may be formed to include a curved surface.For example, a top surface of each of the lens patterns 120 may beformed in a curved shape. For example, each of the lens patterns 120 mayhave a shape of a lenticular lens, an elliptical lens, or the like. Forexample, the cross-sectional shape of the lens patterns 120 may have acurved shape such as a lenticular, an elliptical shape, or the like, butthe present invention is not limited thereto.

Further, a refractive index of the lens patterns 120 may be smaller thana refractive index of the cover film 200, and an aspect ratio of each ofthe lens patterns 120 may range from 0.8 to 1.6. For example, the aspectratio of each of the lens patterns 120 is a value obtained by dividing athickness (e.g., a height) T of each of the lens patterns 120 by a widthW of each of the lens patterns 120. The thickness of each of the lenspatterns 120 may be a vertical distance to a vertex of each of the lenspatterns 120 from the base member 110, and the width W may be a width ofa portion of each of the lens patterns 120 in contact with the basemember 110. When the optical film in which the aspect ratio of each ofthe lens patterns 120 is in a range from 0.8 to 1.6 and a refractiveindex of each of the lens patterns 120 is smaller than the refractiveindex of the cover film 200 as described above, a viewing angle of aliquid crystal display to which the optical film is applied may beenlarged in a lateral direction and a front luminance of the liquidcrystal display may be increased.

The thickness T of each of the lens patterns 120 may range from 1 μm to100 μm, and the width W of each of the lens patterns 120 may range from1 μm to 100 μm. When the aspect ratio of the thickness T and width Wranges from 0.8 to 1.6, the viewing angle of the liquid crystal displaymay be enlarged in the lateral direction and visibility thereof may beincreased.

In addition, the refractive index of the cover film 200 may be greaterthan the refractive index of the lens patterns 120 by at least 0.1. Forexample, the refractive index of the cover film 200 may be greater thanthe refractive index of the lens patterns 120 by a value ranging from0.1 to 0.65. Accordingly, when the optical film is applied to the liquidcrystal display, a visibility index and a contrast ratio (CR) may beincreased.

The refractive index of the lens patterns 120 may be in a range from 1.0to 1.49, for example, a range from 1.42 to 1.49. Further, the refractiveindex of the cover film 200 may be in a range from 1.5 to 1.65, forexample, a range from 1.57 to 1.65. When the refractive indices of thelens patterns 120 and the cover film 200 are in the above-mentionedranges, the front luminance of the liquid crystal display and theviewing angle thereof in the lateral direction may be increased.Further, if the refractive indices of the lens patterns 120 and thecover film 200 are set to be larger than the above-mentioned ranges, thetransmittance of the liquid crystal display may be lowered and ayellowish phenomenon may occur.

The optical film may further include an adhesive layer formed on thebase member 110 and formed on a surface opposite to a surface on whichthe cover film 200 is formed. Although it will be described later, theadhesive layer is provided to attach the optical film to a liquidcrystal panel. The adhesive layer may include optically transparentoptical clear adhesive (OCA), optical clear resin (OCR), or the like.

In a method of fabricating the optical film, as shown in FIG. 4, a stepof forming the lens patterns 120 on the base member 110 may beperformed. For example, the lens patterns 120 may be formed on the basemember 110 by preparing a resin film having the above-mentioned range(e.g., from 1.0 to 1.49 or from 1.42 to 1.49) of the refractive index ofthe lens patterns 120 and by forming the resin film by using a mold withintaglios each corresponding to one of the lens patterns 120. In anexemplary embodiment of the present invention, the lens patterns 120 maybe formed by molding resin using a method such as an imprinting method,or the like.

In addition, the cover film 200 may be formed by coating and curingresin having a refractive index ranging from 1.5 to 1.65 or ranging from1.57 to 1.65 on the surface of the base member 110 on which the lenspatterns 120 are formed. However, the present invention is not limitedthereto, for example, a cover film including intaglio patterns havingsubstantially the same shape as the lens patterns 120 of the base film100 may be prepared and adhered to the base film 111.

The resin forming the cover film 200 may include ultraviolet (UV)curable resin, thermosetting resin, or the like, and may includeacrylate-based resin. Accordingly, an optical film may be fabricated bya curing method as described above. Further, the base member 110 and thelens patterns 120 may include UV curable resin, thermosetting resin, orthe like. By additionally including fluorine-based resin to the UVcurable resin, thermosetting resin, or the like of the cover film 200,the base member 110, and the lens patterns 120, the refractive index ofthe lens patterns 120 may be adjusted to the above-mentioned range(e.g., from 1.0 to 1.49 or from 1.42 to 1.49).

FIG. 6 is a perspective view of an optical film according to anexemplary embodiment of the present invention. FIG. 7 is across-sectional view of the optical film of FIG. 6.

Referring to FIGS. 6 and 7, the optical film may include a cover film201 including intaglios 250 corresponding to lens patterns extending inone direction. Hereinafter, the intaglios 250 corresponding to lenspatterns may be referred to as “intaglio lens patterns 250”. Further, anaspect ratio of intaglio lens patterns 250 may range from 0.8 to 1.6,and the refractive index of the cover film 201 may range from 1.5 to1.65. For example, each of the lens patterns extending in one directionmay be formed in a shape of intaglios in the cover film 201 of theoptical film. In this case, the aspect ratio of each of the intagliolens patterns 250 may be in a range from 0.8 to 1.6. As described above,when the optical film in which the aspect ratio of each of the intagliolens patterns 250 is in the range (e.g., from 0.8 to 1.6) and therefractive index of the cover film 201 is in the range (e.g., 1.5 to1.65), is applied to a liquid crystal display, a front luminance of theliquid crystal display and a viewing angle thereof in the lateraldirection may be increased.

The intaglio lens patterns 250 may be formed to extend in one directionof the cover film 201 and may be arranged in parallel to each other. Theintaglio lens patterns 250 may be formed to be spaced apart from eachother at predetermined intervals. In a non-limiting example, theintaglio lens patterns 250 may be arranged to be spaced apart from eachother at regular intervals.

FIG. 8 is a cross-sectional view of an optical film according to anexemplary embodiment of the present invention.

Referring to FIG. 8, the optical film may further include an adhesive 10which is formed on the surface of the cover film 201 on which theintaglio lens patterns 250 are formed. The adhesive 10 may be formed onthe surface of the cover film 201 on which the intaglio lens patterns250 are formed, and may be formed at positions between the intaglio lenspatterns 250. Accordingly, the adhesive 10 might not be formed on theintaglio lens patterns 250. Thus, the optical film may be attached to aliquid crystal panel, which will be described later. Further, since theadhesive 10 is not formed in the intaglio lens patterns 250, distortionof light provided from the liquid crystal panel may be reduced.

FIG. 9 is a cross-sectional view of an optical film according to anexemplary embodiment of the present invention.

Referring to FIG. 9, the optical film may further include a base film111 which is attached to a surface of the cover film 201 on which theintaglio lens patterns 250 are formed. Further, the adhesive 10 foradhering the cover film 201 to the base film 111 may be formed betweenthe cover film 201 and the base film 111, and the adhesive 10 may bedisposed at positions where the intaglio lens patterns 250 are notformed.

In addition, the optical film may further include an air layer 121 atpositions corresponding to the intaglio lens patterns 250 disposedbetween the cover film 201 and the base film 111. The air layer 121 mayhave a refractive index substantially close to 1. Based on a differencebetween the refractive index of the air layer 121 and the refractiveindex of the cover film 201 and the above-described range (e.g., from0.8 to 1.6) of the aspect ratio of each of the intaglio lens patterns250, a viewing angle of the liquid crystal display in the lateraldirection and a front luminance thereof may be increased.

The optical film shown in FIG. 9 may be fabricated, as shown in FIG. 10.Referring to FIG. 10, an adhesive may be coated at positions between theintaglio lens patterns 250 on the cover film 201 and the cover film 201may be laminated with the prepared base film 111.

FIG. 11 a cross-sectional view showing an optical film according to anexemplary embodiment of the present invention. Referring to FIG. 11, theoptical film may further include a filling layer 122 filled in theintaglio lens patterns 250 of the optical film. The refractive index ofthe filling layer 122 may be in a range from 1.0 to 1.49, for example, arange from 1.42 to 1.49. When the refractive index of the filling layer122 is in the range (e.g., from 1.0 to 1.49 or from 1.42 to 1.49),luminance in a forward direction of light traveling from a liquidcrystal display toward the outside may be increased, and a viewing angleof the liquid crystal display in the lateral direction may be increasedbased on a difference in refractive index between the filling layer 122and the cover film 201 and the aspect ratio of each of the intaglio lenspatterns 250 formed in the cover film 201. The filling layer 122included in the intaglio lens patterns 250 of the optical film may beimplemented by filling a resin having the above range (e.g., from 1.0 to1.49 or from 1.42 to 1.49) of the refractive index in positions (e.g.,the filling layer 122) between the cover film 201 and the base film 111,and thus, durability of the optical film may be increased due to theresin filled in the filling layer 122.

In the cross-sectional view, each of the intaglio lens patterns 250 mayhave a shape of a lenticular lens, an elliptical lens, or the like. Theintaglio lens patterns 250 each having a cross-sectional shape of alenticular lens, an elliptical lens, or the like, may be elongated inone direction and arranged in parallel to each other.

A method of fabricating the optical film shown in FIG. 6 may includefabricating the optical film including the intaglio lens patterns 250 ona film including a resin having a refractive index in a range from 1.5to 1.65, or a range from 1.57 to 1.65 based on an imprinting method.

According to an exemplary embodiment of the present invention, a liquidcrystal display including the optical film as described above may beprovided.

The liquid crystal display may include a backlight unit providing light,a liquid crystal panel receiving light from the backlight unit anddisplaying an image in accordance with an applied signal (e.g., imagedata), and an optical film located on an upper side of the liquidcrystal panel. Here, the optical film may include the above-describedoptical film according to an exemplary embodiment of the presentinvention.

FIG. 12 is a cross-sectional view showing a state where an optical filmaccording to an exemplary embodiment of the present invention isattached to a liquid crystal panel in a liquid crystal display.

Referring to FIG. 12, the liquid crystal panel may include a firstsubstrate 400 and a second substrate 500 facing the first substrate 400,and a liquid crystal layer 600 interposed between the first substrate400 and the second substrate 500. Further, an upper polarizing plate 700may be located on an upper side of the liquid crystal panel, and a lowerpolarizing plate 800 may be located on a lower side of the liquidcrystal panel.

The optical film may include a plurality of lens patterns 120 extendingin one direction, and an aspect ratio of each of the lens patterns 120may range from 0.8 to 1.6. The optical film may be attached to an upperside of the upper polarizing plate 700 and an adhesive 20 is interposedbetween the optical film and the upper polarizing plate 700. The upperpolarizing plate 700 may be attached to a position at which an imagedisplayed in the liquid crystal display is viewed by a viewer.

As shown in FIG. 12, the lens patterns 120 may be formed on the basemember 110 to be spaced apart from each other at predeterminedintervals, and the cover film 200 may be formed on the lens patterns120. However, the present invention is not limited thereto, and intagliolens patterns 250 may be included in a cover film 201, as shown in FIG.13. Referring to FIG. 13, a separate base film might not be formed. Inthis case, the intaglio lens patterns 250 may be formed in the coverfilm 201, and the cover film 201 itself may serve as an optical film,and may be attached to the upper polarizing plate 700 of the liquidcrystal panel by using the adhesive 20.

In the intaglio lens patterns 250, as described above, an air layerhaving a refractive index substantially close to 1, or a filling layerhaving a refractive index in a range from 1.0 to 1.49 may be formed.

Hereinafter, elements included in the liquid crystal panel will bedescribed in more detail with reference to FIG. 13.

The liquid crystal panel may have a state in which the liquid crystallayer 600 is interposed between the first substrate 400 and the secondsubstrate 500. The first substrate 400 may be a thin film transistor(TFT) array substrate. For example, a liquid crystal driving electrode,a wiring pattern, a thin film transistor, an alignment layer, or thelike may be formed on the first substrate 400. For example, the liquidcrystal panel may include a thin film transistor and a pixel electrodeon a base member made of a transparent insulating material such asglass, plastic, or the like. The thin film transistor may include a gateelectrode, a gate insulating film, a semiconductor layer, an ohmiccontact layer, and source/drain electrodes. The pixel electrode may be afield generating electrode formed of transparent conductive oxide, suchas ITO, IZO, or the like.

On a surface of the second substrate 500 facing the first substrate 400,color filters, a common electrode, an alignment layer, or the like maybe formed. A black matrix may also be formed on the surface of thesecond substrate 500. For example, the second substrate 500 may includea black matrix, a red color filter, a green color filter, a blue colorfilter, and a common electrode on a lower surface of the base membermade of a transparent insulating material such as glass, plastic, or thelike. The black matrix may act to prevent light leakage. The commonelectrode may be a field generating electrode formed of transparentconductive oxide such as ITO, IZO, or the like.

For the first substrate 400 and the second substrate 500, plasticsubstrates such as polyethylene terephthalate (PET), polycarbonate (PC),polyimide (PI), polyethylene naphthalate (PEN), polyether sulfone (PES),polyarylate (PAR), cycloolefin copolymer (COC), or the like may be used,but the present invention is not limited thereto. Further, the firstsubstrate 400 and the second substrate 500 may be formed of a flexiblematerial.

The upper polarizing plate 700 may be disposed on the second substrate500 of the liquid crystal panel, and the lower polarizing plate 800 maybe disposed below the first substrate 400 to transmit light with aspecific state of polarization. In the case of providing the upperpolarizing plate 700 and the lower polarizing plate 800, transmissionaxes of the polarizers of the polarizing plates 700 and 800 may besubstantially parallel or perpendicular to each other.

An operation mode of the liquid crystal panel may include, for example,a twisted nematic mode or an electrically controlled birefringence mode.The electrically controlled birefringence mode may include a verticalalignment mode, an optically compensated bend (OCB) mode, an in-planeswitching (IPS) mode, or the like.

Among the operation modes of the liquid crystal panel, a TN mode will bedescribed as an example. If an electric field is not formed in theliquid crystal panel, since there is no voltage difference between thepixel electrode and the common electrode (e.g., the field generatingelectrodes), liquid crystal molecules of the liquid crystal layer 600 inthe liquid crystal panel may be arranged such that major axes of theliquid crystal molecules are arranged to be parallel to the surfaces ofthe first substrate 400 and the second substrate 500. Thus, the liquidcrystal molecules may have a structure in which the major axes thereofare spirally twisted by 90° starting from the first substrate 400 up tothe second substrate 500.

In this case, the polarization of the linearly polarized light may bechanged by the retardation caused by the refractive index anisotropy ofthe liquid crystal molecules when the light passes through the liquidcrystal layer 600. By adjusting a chiral pitch and dielectric anisotropy(Δ∈) of the liquid crystal or a thickness (e.g., cell gap) of the liquidcrystal panel, the polarization state of the linear polarized light maybe adjusted to be rotated by 90° when passing through the liquid crystalpanel.

In addition, the upper polarizing plate 700 may include a polarizer 730including a polyvinyl alcohol-based film on which an iodine or adichroic dye is adsorbed and oriented, and polarizer protecting films710 and 720 may be attached to top and bottom portions of the polarizer730, respectively. In addition, the lower polarizing plate 800 mayinclude a polarizer 830 including a polyvinyl alcohol-based film onwhich an iodine or a dichroic dye is adsorbed and oriented, andpolarizer protecting films 810 and 820 may be attached to top and bottomportions of the polarizer 830, respectively. In an exemplary embodimentof the present invention, one of the polarizer protecting films may beomitted. For example, the polarizer protecting film 710 formed on thesurface of the upper polarizing plate 700 to be attached to the liquidcrystal panel may be omitted and may be attached to the liquid crystalpanel by an adhesive.

FIG. 14 is a cross-sectional view showing a liquid crystal displayaccording to an exemplary embodiment of the present invention. Theliquid crystal display of FIG. 14 employs an edge type backlight unit,and may include at least one light source 900, a light guide plate (LGP)1000 disposed on a side of the light source 900 to guide light emittedfrom the light source 900, a liquid crystal panel disposed on an upperside of the light guide plate 1000 to display an image in accordancewith an applied signal, and a variety of optical plates 1200 and 1300located between the light source 900 and the liquid crystal panel.Further, a reflective sheet 1100 may be disposed on a lower surface ofthe light guide plate 1000.

The light source 900 may be disposed on at least one side of the lightguide plate 1000. FIG. 14 illustrates a case where the light source 900is disposed on only one side of the light guide plate 1000, but thepresent invention is not limited thereto, and for example, a pluralityof light sources may be employed and arranged on one side or more thanone side of the light guide plate 1000.

The light source 900 may include, for example, a light emitting diode(LED), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescentlamp (HCFL), an external electrode fluorescent lamp (EEFL), or the like.

The light guide plate 1000 may guide the light emitted from the lightsource 900 through total internal reflection, reflect the guided lightthrough a scattering pattern, or the like, formed on the lower surfaceof the light guide plate 1000, and emit the reflected light in an upwarddirection. The reflective sheet 1100 may be disposed below the lightguide plate 1000 to reflect light emitted downward from the light guideplate 1000 in an upward direction.

The light guide plate 1000 may be made of a light transmitting materialhaving a constant refractive index, such as poly methyl methacrylate(PMMA), polycarbonate (PC), or the like, but the present invention isnot limited thereto.

An optical plate may be disposed on the light guide plate 1000. Theoptical plate may include a diffusion sheet 1200 and a prism sheet 1300.

The diffusion sheet 1200 may diffuse and transmit a part of the lightpropagating from the light source 900 toward the liquid crystal panel,and reflect another part of the light back to a lower side of thediffusion sheet 1200. The liquid crystal panel may be disposed on anupper side of the diffusion sheet 1200. In an exemplary embodiment ofthe present invention, the diffusion sheet 1200 may be formed ofpolymethyl methacrylate (PMMA), polystyrene (PS), polycarbonate (PC),cyclo-olefin copolymers (COC), polyethylene terephthalate (PET),polybutyleneterephtalate (PBT), plastic alloy, or the like, but thepresent invention is not limited thereto.

In addition, the optical plate may further include a microlens arrayfilm, a lenticular lens film, or the like. As shown in FIG. 14, aplurality of optical plates may be employed. An arrangement of theoptical plates may be changed in various ways.

Since the liquid crystal panel has been described above, a repeateddescription will be omitted.

FIG. 15 is a cross-sectional view showing a liquid crystal displayaccording to an exemplary embodiment of the present invention. Theliquid crystal display of FIG. 15 employs a direct type backlight unit.

The liquid crystal display may include at least one light source 900, aliquid crystal panel, which is disposed on an upper side of the lightsource 900 to display an image, and optical plates 1200 and 1300 locatedbetween the light source 900 and the liquid crystal panel.

The liquid crystal display may be configured such that the light emittedfrom the light source 900 disposed in a lower side of the liquid crystaldisplay is uniformly dispersed by the diffusion sheet 1200 at an upperside thereof, is condensed by the prism sheet 1300, and is provided tothe liquid crystal panel at an upper side thereof. Since the liquidcrystal panel, the light source 900, the diffusion sheet 1200, and theprism sheet 1300 have been described above, a repeated description willbe omitted.

A backlight assembly including the light source, the light guide plate,the reflective sheet, the optical plate, or the like may be accommodatedin a bottom chassis, and the liquid crystal panel may be mounted on anintermediate frame and fixed to a top chassis on an upper side of theliquid crystal display. The top chassis may include a portion to exposea display area where an image is displayed. By coupling the top chassis,the bottom chassis, and the intermediate frame, the respective elementsconstituting the liquid crystal display may be fixed and accommodated inthe liquid crystal display.

Hereinafter, an optical film according to an exemplary embodiment of thepresent invention will be described in more detail using variousexamples.

Example 1

An optical film is fabricated by forming a cover film having arefractive index of 1.57 on a base film, which is made of resin having arefractive index of 1.42 and on which lens patterns are formed, and byadjusting a width and a thickness of each of the lens patterns to 9.9 μmand 10.7 μm, respectively. In this case, an aspect ratio of thethickness to the width is about 1.08.

Example 2

An optical film is fabricated in substantially the same manner as inexample 1 except that the width and thickness of each of the lenspatterns are adjusted to 10.1 on and 15.3 μm, respectively. In thiscase, the aspect ratio of the thickness to the width is about 1.51.

Example 3

An optical film is fabricated by forming a base film and a cover filmwithout forming lens patterns.

Example 4

An optical film is fabricated in substantially the same manner as inexample 1 except that the width and thickness of each of the lenspatterns are adjusted to 11.9 μm and 6.0 μm, respectively. In this case,the aspect ratio of the thickness to the width is about 0.50.

Example 5

An optical film is fabricated in substantially the same manner as inexample 1 except that the width and thickness of each of the lenspatterns are adjusted to 10.4 μm and 20.0 μm, respectively. In thiscase, the aspect ratio of the thickness to the width is about 1.92.

Example 6

An optical film is fabricated in substantially the same manner as inexample 1 except that the width and thickness of each of the lenspatterns are adjusted to 8.3 μm and 27.8 μm, respectively. In this case,the aspect ratio of the thickness to the width is about 3.35.

Example 7

An optical film is fabricated in substantially the same manner as inexample 1 except that the width and thickness of each of the lenspatterns are adjusted to 10.1 μm and 24.2 μm, respectively. In thiscase, the aspect ratio of the thickness to the width is 2.40.

A visibility index, a contrast ratio (CR), and a viewing angle of aliquid crystal display to which the optical film fabricated according toat least one of the above-described examples is applied were measured,and the measurement results are shown in Table 1 below.

TABLE 1 Aspect ratio Visibility index CR Viewing angle (°) Example 11.08 0.28 6184:1 57 Example 2 1.51 0.26 5203:1 58 Example 3 — 0.387224:1 49 Example 4 0.50 0.35 6305:1 51 Example 5 1.92 0.25 3541:1 58Example 6 3.35 0.23 2035:1 65 Example 7 2.40 0.21 2614:1 63

The visibility index in Table 1 is a numerical value corresponding to adifference between a Gamma value measured at the front of the liquidcrystal panel and a Gamma value measured at a viewing angle of 60° ofthe liquid crystal panel for each gray scale. For example, a visibilityindex having a value close to 0 may be understood such that there is nodifference in, e.g., gamma value, between the front and the side of theliquid crystal panel. Thus, for example, as the visibility indexapproaches a value of 0, visibility of the liquid crystal panelincreases. As can be seen in example 1 or 2, which was fabricated withthe particular refractive indices, widths, and thicknesses according toan exemplary embodiment of the present invention as described above, thevisibility index is low (e.g., less than 0.3), and thus, the opticalfilm made in accordance with an exemplary embodiment of the presentinvention may have excellent visibility characteristics.

The CR in Table 1 is a numerical value obtained by dividing whiteluminance by black luminance. For example, the CR which is equal to orgreater than 5000:1 may be understood as excellent CR characteristics.The CR values of the liquid crystal display, to which the optical filmfabricated based on example 1 or 2 according to an exemplary embodimentof the present invention is applied, are equal to or greater than5000:1, and thus, the optical film fabricated based on example 1 or 2may have excellent CR characteristics.

The viewing angle in Table 1 indicates a range of a viewing angle atwhich luminance is 50% of the front luminance. For example, the viewingangle having a high value may be understood such that side visibility ofthe liquid crystal display is excellent and the viewing angle of theliquid crystal display is wide. The liquid crystal display to which theoptical film fabricated according to an exemplary embodiment of thepresent invention is applied may have an excellent viewing angle.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention.

What is claimed is:
 1. An optical film comprising: a base film includinga base member and a plurality of lens patterns disposed on the basemember, wherein the plurality of lens patterns protrudes from the basemember and extends in a first direction; and a cover film disposed onthe base film to cover the base member and the plurality of lenspatterns, wherein a refractive index of at least one of the lenspatterns is smaller than a refractive index of the cover film, andwherein an aspect ratio of the at least one of the lens patterns rangesfrom 0.8 to 1.6.
 2. The optical film of claim 1, wherein the refractiveindex of the cover film is larger than the refractive index of the atleast one of the lens patterns by 0.1 to 0.65.
 3. The optical film ofclaim 1, wherein at least one of the lens patterns has a shape of alenticular lens or an elliptical lens.
 4. The optical film of claim 1,wherein the refractive index of the at least one of the lens patternsranges from 1.0 to 1.49.
 5. The optical film of claim 1, wherein therefractive index of the at least one of the lens patterns ranges from1.42 to 1.49.
 6. The optical film of claim 1, wherein the refractiveindex of the cover film ranges from 1.5 to 1.65.
 7. The optical film ofclaim 1, wherein the refractive index of the cover film ranges from 1.57to 1.65.
 8. The optical film of claim 1, further comprising an adhesivelayer formed on the base member and formed on a surface opposite to asurface on which the cover film is formed.
 9. An optical filmcomprising: a cover film including intaglios of a plurality of lenspatterns extending in a first direction, wherein an aspect ratio of atleast one of the intaglios of the lens patterns ranges from 0.8 to 1.6,and wherein a refractive index of the cover film ranges from 1.5 to1.65.
 10. The optical film of claim 9, further comprising a base filmwhich is attached to a surface of the cover film on which the intagliosof the lens patterns are formed.
 11. The optical film of claim 10,further comprising an air layer in the intaglios of the lens patternsdisposed between the cover film and the base film.
 12. The optical filmof claim 9, further comprising an adhesive formed on a first portion ofa surface between the cover film and the base film, wherein theintaglios of the lens patterns are not formed on the first portion ofthe surface.
 13. The optical film of claim 9, further comprising afilling layer disposed in the intaglios of the lens patterns of thecover film, wherein a refractive index of the filling layer ranges from1.0 to 1.49.
 14. The optical film of claim 9, wherein at least one ofthe intaglios of the lens patterns has a shape of a lenticular lens oran elliptical lens.
 15. A liquid crystal display comprising: a backlightunit; a liquid crystal panel for receiving light from the backlight unitto display an image; and an optical film disposed on an upper side ofthe liquid crystal panel, wherein the optical film includes a pluralityof lens patterns extending in a first direction, and an aspect ratio ofat least one of the lens patterns ranges from 0.8 to 1.6.
 16. The liquidcrystal display of claim 15, wherein the optical film includes a basefilm including a base member and the plurality of lens patterns, and acover film formed on the base film to cover the base member and theplurality of lens patterns, and wherein a refractive index of the atleast one of the lens patterns is smaller than a refractive index of thecover film.
 17. The liquid crystal display of claim 16, wherein therefractive index of the at least one of the lens patterns ranges from1.0 to 1.49, and the refractive index of the cover film ranges from 1.5to 1.65.
 18. The liquid crystal display of claim 15, wherein the opticalfilm includes a cover film which is attached to an upper side of theliquid crystal panel, and the plurality of lens patterns are formed asintaglios in the cover film.
 19. The liquid crystal display of claim 18,further comprising an adhesive formed on a first portion of a surfacebetween the cover film and the liquid crystal panel, wherein theintaglios of the lens patterns are not formed on the first portion ofthe surface.
 20. The liquid crystal display of claim 18, furthercomprising an air layer in each of the intaglios of the lens patterns ora filling layer disposed in each of the intaglios of the lens patterns,wherein a refractive index of the filling layer ranges from 1.0 to 1.49,and a refractive index of the cover film ranges from 1.5 to 1.65.